This project will investigate the incidence and causes of incest and family sexual abuse. Based on scattered reports, we estimate that between 5 and 15% of all women have experienced sexual abuse within their own families. We intend to test this estimate and to gather information to better describe and account for the abuse that takes place. Six models or theories of sexually abusive families will be tested. We anticipate all of them will contribute to some degree. We would like to disentangle the relative importance of each and each's general applicability: 1) Personality of the offender. 2) Nature of the marital relationship. 3) Family atmosphere of abandonment. 4) Subcultural attitudes toward incest. 5) Family sexual culture. 6) Situational factors. The study will also bring evidence to bear on controversies surrounding the source of the normal "incest taboo." To what extent is this taboo the result of (1) powerful social norms, or (2) the vigilance of family members over one another, or (3) a natural sexual aversion that develops out of family interaction? Four hundred undergraduates at two universities will complete anonymous questionnaires about sexual behavior. A subsample of these students will be personally interviewed to enrich the questionnaire findings, and to explore hypotheses beyond the scope of the larger survey. The practical use of the findings of this study should be apparent. Almost everything currently known about sexual abuse in families is based on families which come to the attention of mental health or criminal justice officials. Public policy is stymied without a true estimate of the extent of the problem. Prevention is haphazard until we can identify families and children who are at risk. And treatment programs may be inefficient and ineffective if they are based on speculative theories about the source of the problem.